On the application of decorative UV screen printin

Discussion on the application of decorative UV printing ink

in recent years, with the development of UV ink and UV curing technology, decorative UV printing ink is more and more widely used in packaging and printing. Using decorative UV printing ink can produce some special artistic effects after printing, so as to decorate and beautify the printed matter

commonly used decorative UV printing inks

there are mainly the following kinds of decorative UV printing inks

printing imitation metal etching ink

uv printing imitation metal etching ink is usually printed on gold and silver card paper with high gloss. The frosting effect produced on the surface of the printed matter makes the printed matter have a suspended three-dimensional feeling, rich, luxurious and unique. It is widely used in packaging and printing, especially in cigarette boxes and wine boxes. Generally, there are sanding inks of different thickness to choose from

wrinkle printing ink

uv wrinkle printing ink is usually printed on gold and silver card paper with high gloss. The printed matter is first irradiated by weak UV light, so that the surface of the ink is completely cured, and the interior is in a semi cured state. The UV ink on the surface has a concave convex texture due to curing shrinkage. Then, through strong UV light irradiation, the UV ink is solidified as a whole (external and internal), and the surface effect of metal hammering or folding can be achieved. Wrinkle printing is elegant and noble, with good decorative effect. It is commonly used in the printing of cigarette boxes, wine boxes, gift boxes, cosmetic boxes, calendars, books, etc

coral printing ink

uv coral printing ink is usually printed on gold and silver card paper with high gloss. At the same time of printing, the ink bubbles. This kind of bubbles gather mutually, and the irregular continuous accumulation and bubble free rubber tensile testing machine do not need a lot of force to smooth the part together to form a coral like texture, which can also be said to form a three-dimensional coral like texture instantly

ice print ink

uv ice print ink is usually printed on gold and silver card paper with high gloss. The printed matter is first irradiated by weak UV light to solidify the ink surface and semi solidify the inside. Then, through strong UV light irradiation, all UV inks (external and internal) are solidified to produce ice effect. Generally, there are inks with different ice effect sizes to choose from

printing refractive ink

uv printing refractive ink is suitable for printing on all kinds of gold, silver cardboard and mirror paper with specially made plates. After UV light irradiation, the ink film has obvious refractive effect

printing crystal grain ink

uv printing crystal grain ink adds blocking agent. Because the surface curing speed is different from the internal curing speed, it forms crystal grain, which is mainly used in the decorative process of crystal grain on the surface of glass and metal

Decorative UV printing ink printing process

in order to ensure the printing quality of decorative UV printing ink, the following process factors should be paid attention to when printing

1. Mesh count

UV inks for different purposes have different mesh counts when printing due to different printing requirements. Generally, the higher the fineness of the printed matter, the higher the number of silk meshes required to be selected. When printing eye tone products, it is generally required that the ratio of the number of selected silk meshes to the number of added threads be greater than 4.2

for the printing of decorative UV ink, the number of wire mesh should be selected according to the specific requirements of the ink. For example, when using UV printing imitation metal etching ink for printing, the number of wire mesh should be selected to match the thickness of the ink sand mold. If the sand mold is coarse and the particle size is large, the wire with lower mesh number should be selected, and the pore diameter of the wire is large, which can make the ink leak to the substrate through the wire. Otherwise, part of the ink will remain on the plate, resulting in less sand on the print. 6. According to the structural principle, it can be divided into electronic, hydraulic, mechanical, servo experimental machines, etc; Moreover, with the progress of printing, the viscosity of the ink on the plate gradually increases, and the ink particles continue to accumulate. If the sand mold is fine and the particle size is small, the wire with higher mesh number can be selected. Generally, the mesh number of wire is 150 ~ 250 mesh/inch, and the higher the mesh number, the finer the sand grain printed

when using UV wrinkle printing ink, the number of silk meshes can be selected according to the size of wrinkles to be achieved. The higher the number of silk meshes, the smaller the wrinkles, and vice versa. Generally, the number of wire mesh is 120 ~ 200 mesh/inch. When UV printing coral ink is used for printing, the situation is similar to that of UV printing wrinkle ink. The number of wire mesh can be selected according to the size of coral ripple to be achieved. The higher the number of wire mesh, the smaller the coral ripple, and vice versa. For UV printing ice flower ink, the number of wire mesh selected should match the size of ice flower

2. When printing, the distance between the plate and the substrate (i.e. distance) also has a great impact on the printing effect. The distance is too small, the imprinted edge is not clear, and the effect of decorative ink printing is not obvious; If the distance is too large, it will have a certain impact on the printing accuracy, and even tear the wire. Therefore, the printing time interval should be appropriate

3. Scraper angle

scraper angle is related to the ink output during printing. The scraper angle is large, the ink output is small, the ink color of the printed matter is light, and the effect of decorative ink is not obvious after printing; If the angle of the scraper is too small and the ink output is too large, the ink will spread seriously and the printing precision will be affected to a certain extent. Therefore, the angle of the scraper should be appropriate during printing

4. Printing pressure

printing pressure also affects the ink output during printing. The printing pressure is small, the ink output is small, the ink color of the printed matter is light, and the effect of decorative ink is not obvious after printing; Excessive printing pressure and excessive ink output will cause serious ink spreading and even tear the silk. Therefore, the printing pressure should be appropriate

5. Printing speed

the printing speed will also affect the ink output during printing. The printing speed is too fast, the ink output is small, and the ink color of the printed matter is light. In addition, the printing effect of decorative ink is not obvious, so the printing speed cannot be too fast

of course, the above process conditions should also match each other. For example, if the printing speed is fast, larger printing pressure and smaller scraper angle should be selected for printing, and the viscosity of the ink should not be too high

curing light source

because the curing of UV ink depends on the polymerization and cross-linking reaction after the photoinitiator absorbs the radiant energy of UV light, the selection of UV light source has a crucial impact on the curing speed of UV ink. The following factors should be considered when selecting the curing light source

(1) the output spectrum of the light source should match the absorption spectrum of the photoinitiator as much as possible, so as to maximize the use of the radiation energy of the light source and produce more free radicals, so as to improve the curing speed of UV ink. The commonly used UV curing light source is the medium pressure mercury lamp (included in the high-pressure mercury lamp in China), which mainly emits light of the following wavelengths: 405nm, 365 ~ 366nm, 312 ~ 313nm, 302 ~ 303nm, 297nm, 265nm, 254nm and 248nm

(2) the efficiency of converting electric energy into UV light energy should be high

(3) the light intensity should be appropriate. If the strength is too high, the free radicals will be produced quickly, and if the concentration is too high, the termination reaction speed will be accelerated, which will have an adverse impact on the cross-linking reaction; The strength is too low, the speed of producing free radicals is too slow, and the oxygen polymerization inhibition effect will be very strong, which will make the curing speed of UV ink too slow

(4) long service life. UV lamps will gradually age, and the light intensity of expired UV lamps will decrease a lot, making the curing of UV ink too slow

(5) there should be a good lampshade to focus light. The quality of the lampshade has a great impact on the curing efficiency of UV ink. For the same UV lamp, the curing efficiency of ink can even differ by more than ten times with different lampshades

(6) the shape of UV lamp is appropriate, which can make the light shine evenly on the printed matter, and it is easy to install, cheap, safe and reliable. Generally, tubular lamp is used

(7) since ozone will be produced in the air under the irradiation of UV lamp, ventilation equipment should be provided

the power density of the medium pressure mercury lamp used for curing colored ink is generally 120w/cm, and the power density of the medium pressure mercury lamp used for curing colorless ink is 80w/cm. The lamp length can range from a few centimeters to 200cm, and the diameter is 15 ~ 25cm. Due to its high temperature in application, it needs to be cooled, and its service life is generally about 1000 hours. Mercury lamps need ballasts. The light intensity of the lamp is certain, and the current and voltage can be adjusted, or high current and low voltage, or low current and high voltage

a period of preheating time is required after the mercury lamp is turned on. Rock blocks refer to geological blocks to facilitate the evaporation of mercury. During the mercury lamp preheating period, in order to adjust and cut off the material flow, the expected UV light cannot be obtained. After the mercury lamp is turned off, it cannot be started again immediately. It needs to be cooled for a period of time, which will bring some inconvenience to the use. Now, a kind of electrodeless mercury lamp has been introduced in the market, which can be switched on and off instantaneously, with long service life and great efficiency. The spectrum of the electrodeless mercury lamp used for UV curing is continuous, which is different from the medium pressure mercury lamp, and can be used for the curing of thick films